You have a bundle of multicoloured threads, let’s say, and as you walk down a crowded sidewalk you absent-mindedly pull a few out with your left hand and run your right thumb across them, making a bit of a casual hum in the throng. You look up and see a friend approaching and, in your distraction, you thump your elbow on a post as you pass, snapping a string. You don’t notice until your friend says, “What’s that blue thing on your thumb?” You reply, catching yourself as you look: “It’s a thr— um…”
Thrum, thrum, thrum. You have thrummed on a thrum with your thumb as a thrum thrummed about you, and with a thump you thrummed your thumb; now your thumb makes no thrum but has a thrum. All together now, one, two, three: Um… what?
There are three thrums (a trithrumvirate?), each with a different meaning, each a native English word (i.e., not adopted from another language), each thrum from a different source, and each having both noun and verb form. Ain’t that thrumthing!
The one we all know now is what one does on a guitar or similar instrument: you may thrum it or produce a thrum. This is onomatopoeia, the /r/ giving the rolled sound and the /m/ the sustained hum, with the voiceless fricative to start with simply giving a soft start, softer than in strum. It is also the newest of the three thrums, appearing first in the 1500s. And I should add that in some dialects it also refers to the purring of a cat… Can’t you just hear it?
The other thrum still in some form of use is the one referring to a loose end of thread, a bit too small to be of much use. But not no use at all: one may make a thrum cap or thrum mop. And thrum also gets (or, in the main, got) use in such pairings as thrum beard and thrum-chinned, which give a picture of a sort of scraggly long stubble. As a verb it means “decorate with thrums” (as opposed to “make a thrum”). It comes from an Old German word meaning “end-piece” or “remnant”; trace it back to Indo-European and up into Latin and you will find terminus at the end of your thread.
And then there is the thrum that means “crowd”, “throng”, or “bunch” or, as a verb, “crowd” or “cram”; it has been out of use for half a millennium. I know you’re wondering whether it’s related to throng and its source thring. Well, it doesn’t seem to be; thring comes from a verb focusing on the agitation of a crowd, and had forms þring, þrang, þrong, whereas thrum’s source focused on multitude and magnitude and strength, and got to us by way of þrymm. (That þ letter is thorn, the old way we represented the voiceless “th” sound.)
The sounds of thrum have a sort of soft warmth, and perhaps a bit of heaviness, no? It is in the same general set, aesthetically, and throb and hum but not so much as thrust or thrash or thrill. And in the act of saying it, your tongue strokes back from your teeth across your alveolar ridge, culminating with the lips closing – not altogether unlike the gesture of a hand thrumming just once on a guitar… or perhaps, better, a theorbo.
Thanks to Margaret Gibbs for suggesting thrum… a year and a half ago. You see, I do get to them all eventually…